Cold Air Moves In Tonight, But The Nippiest Time Will Be Sunday Morning.

A blast of Canadian air was expected to produce the coldest temperatures of the season, with lows on Saturday and Sunday in the upper 30s inland and the mid 40s at the coast.

Add 10-15 mph breezes, and it might feel close to freezing. The far western suburbs might even see patches of frost, the National Weather Service in Miami said.

"It's going to be cold, at least by our standards, 15 to 20 degrees below normal," said meteorologist Robert Molleda.

The chilly air was to flow into the region by this evening on the heels of a strong cold front that already has put the Midwest into a deep freeze. Until the brisk conditions arrive, today should be mostly cloudy and breezy with a slight chance of rain.

While Saturday was forecast to be mostly sunny and breezy, high temperatures were to reach only into the low to mid 60s. Sunday morning could be the nippiest point in the snap, and some areas near Lake Okeechobee might see the mercury dip near freezing, Molleda said.

By Sunday afternoon, temperatures were to warm into the low 70s. Cool to temperate conditions should linger for a few days, with Monday's high forecast to be in the mid 70s.

Broward and Miami-Dade counties planned to open homeless shelters on Friday night. Palm Beach County officials said a decision would be made today.

"If they have anything real fragile, they should bring it inside by Friday afternoon and keep it in until Sunday afternoon," said Darren Parmenter, agricultural agent with the Palm Beach County Cooperative Extension Service.

Fruit and vegetable farms and nurseries already are taking precautions, he said. Some have hired helicopters to circulate the air above crops and plants.

"That actually warms the air," Parmenter said.

Central and North Florida also were bracing for shiver weather.

Today's low temperatures were forecast to be 25 in Tallahassee, 35 in Orlando and 38 in Tampa.

Because January is the coldest month in South Florida, more cold snaps could be on the way, Molleda said. On the other hand, he added, "It's possible this could be coldest of the season."